Braking mechanism



Jan. 29, 1952 s, sc 2,583,888

BRAKING MECHANISM Filed April 3, 1950 2 SHEETS-SHEE'1' 1 FIG .l.

INVENTOR'.

HIS ATT RNEYS.

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BRAKING MECHANISM 2 Sl'iEETS-SPEET 2 Filed April 5, 1950 INVENTDRI a aken/14 l w ms ATT'ORN s.

Patented Jan. 29, 1952 BRAKING MECHANISM Steve Schnell, Kirkwood, Mo., asslgnor t'o Wagner Electric Corporation, St. Louis, Mo., :1 corporation of Delaware Application April 3', 1950, Serial No. 153,595

3 Claims. I

This invention relates to hydraulic braking. mechanism for motor vehicles and is more particularly directed to an improved brake construction.

One of the objects of the invention is to provide a brake construction that will permit equal energization of both brake shoes when said brake is applied with the motor vehicle moving in a forwardly direction.

Another object of the invention is to produce a two-shoe brake wherein at least one of said shoes is self-centering during a. braking application.

Still another object of the invention is to provide a simplified brake construction wherein the abutments for receiving the brake shoe torque are a part of the fluid motors which are responsible for the initial actuation of the brake shoes.

A further object of the invention is to provide novel means associated with the abutment means for receiving the torque of the brake shoes and for adjusting lining wear of one or more of said brake shoes.

This invention consists in the provision of a hydraulic brake for automotive vehicles having, a pair of brake shoes supported on a backing plate and adapted for movement toward and away from a brake drum, the movement being accomplished by a fluid motor interposed between the adjoining ends of the brake shoes. the motors being so organized and arranged that two shoes are effective during the forward rotation of the brake drum, one shoe being more eiiective than the. other during reverse rotation and wherein the brake thrust or torque is taken by the fluid motors applying the shoes in either direction of drum rotation.

In the drawings:

Fig. 1 is an elevational view of a brake assembly with parts in section to show detail,

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1,

Fig. 3 is a sectional view taken substantially along the line 3-3 of Fig. l; and.

Fig. 4 is a sectional view taken substantially along the line 4--4 of Fig. 1. I

The invention is embodied in the several views of the drawings in which the numeral I designates the backing plate for the brake assembly which is normally attached to the motor vehicle axle (not shown). This plate supports fluid motors 2 and 3 and the fluid motors are each attached to the backing plate I by mounting screws 4. The motor 3 consists of a body member 5 having a cylindrical bore 6 in which pistons l. are slidably mounted. Piston packing cups 8 are mounted in bore 6 in contact with the opposed. faces of pistons I for preventing leakage of fluid pressure past the pistons, and interposed between said cups for holding them in contact with the faces of said pistons is a spring 9. The cylindrical bore 6 is provided. with an inlet port in and an outlet port II, each communicating with bore 6 at a point between the aforementioned packing cups 8. A boot i2 is provided around the left end of bore 6 for preventing ingress of dirt and other foreign matter into the bore. The right hand piston I is provided with a piston rod [3 extending through a small bore 14 in the body member 5 and sufllci'ently beyond the body member for engagement with the end of a brake shoe 15 to be later described. A seal I6 surrounds the piston rod l3 of piston i for preventing the possibility of foreign matter entering the bore 6. The left hand piston I is provided with a hardened insert H which constitutes a workable connection be tween the piston and the brake shoe 13 to be hereinafter described.

The fluid motor 2 is located on the backing plate I diametrically opposite the fluid motor 3 and consists of a body member I9 secured to the backing plate I by mounting screws 4 The body member has a cylindrical bore 20 therein, the open end of said bore being closed. by a cylindrical plug 2| having a cylindrical bore in which a piston 22 is slidably mounted. A packing cup 23 is in contact With piston 22 and prevents the escape of fluid past the piston, a spring 24 holding cup 23 in contact with piston 22. The piston 22 is also provided with a piston rod 25 protruding beyond the end of the body member l9 through a bore 26 in the plug 2| a suflicient distance that it has working contact with the brake shoe l5. The plug 2| is provided with a fluid seal 21 for preventing loss of pressure fluid between the plug and the body member I9, and a seal 28 in bore 26 about rod 25 excludes foreign matter which might otherwise get into the bore 20. An inlet port 29 and a bleeder port 30 are provided near the closed end of bore 20. The inlet port 29 of fluid motor 2 is connected by a suitable conduit (not shown) to the outlet port II of fluid motor 3.

Adjacent to the left end of the fluid motors 2 and 3 is a forward shoe i3 slidably anchored to the backing plate I by a stud 31 which extends through an aperture 32(Fig. 3) provided in the web portion 33 of shoe [8. Attached to the web portion of shoe I8 is a table portion 34 to which the friction lining member 35 is secured. The toe portion 36 of the shoe I8 i held in contact with insert H of fluid motor 3 by a return spring 31, one end of which is hooked in aperture 38 cut in web 33 of shoe I8, the opposite end of the spring being hooked in aperture 39 out in reverse shoe I5, The heel portion 46 of shoe I8 is in contact with abutment 4I forming a part of the body member I9 of fluid motor 2. It is held in contact therewith by another return spring 42 hooked in apertures 43 and 44 in shoes I and I8 in the same manner as return spring 31. The shoe I8 is manually adjustable in relation to brake drum 45 by means of the adjusting cam 46 mount ed on stud 3 I.

Diametrically opposite the forward-shoe I8 is reverse shoe I5, the ends of which are adjacent to the fluid motors 2 and 3. The reverse shoe is slidably mounted on the backing plate I on stud 41 secured thereto in a suitable manner. This studs extends through an aperture cut in web 48 of shoe I5. A Washer 49 abuts a collar formed on stud 4! and a spring washer 56 is interposed between web 48 and washer 49. A washer 5! is disposed on the opposite side of web 48 and a C washer 52 holds the washers and shoe !5 in assembled relation, the C washer being secured to the stud in the conventional manner. The web 48 has a table 53 secured thereon to which a friction lining 54 is secured in the customary manner. The toe 55 of the reverse shoe is held in contact with the piston rod I3 of piston I by return spring 31. The heel 56 on shoe I5 is held in contact with piston rod by return spring 42.

An abutment 5! is formed on the body member 5 of fluid motor 3 having a surface thereon radially of the center of the backing plate I. An abutment 58 formed on plug 2| of fluid motor 2 has a surface thereon radially of the backing plate, thus allowing the brake shoe I5 to selfcenter during a braking operation. The brake shoe I5 is manually adjusted by screwing the plug 2| inwardly or outwardly, as the case may be, for obtaining the proper clearance between the friction 1ining 54 of shoe I5 and the brake drum 45 and by reason of the conical shape of the right hand end of plug 2 I, the abutment 58 will always be substantially radially of the center of the backing plate I. The forward shoe I8 is always in engagement with abutment M of fluid motor 2 which is substantially radially of the center of the backing plate, thus permitting a self-centering action of said shoe I8.

The shoe I8 is adjusted toward and away from brake drum 45 by cam 46 secured to stud 3 I. The.

cam engages a pin 46' secured to web 33 of the shoe I8 as the cam is rotated, thereby moving the shoe I8 outwardly. The angle of contact between pin 46' and cam 46 is opposite to the angle of contact between heel 40 of shoe I8 and abutment 4|. If this were not true, when cam 46 is turned inlet port 29 of the fluid motor 2 to force piston 22 toward the right. Simultaneously, the pressure fluid in bore 6 of fluid motor 3 forces piston I toward the ends of the cylinder bore 6. The left hand pisto'n I of the fluid motor will, by reason of its engagement with the toe of shoe I8, force in a counter-clockwise direction, the shoe would the stud 3|, and nut 64 threaded to stud 3I ten-.

sions the spring. The brake shoe I8 is adjusted vthe shoe outwardly into contact with the brake drum 45 while the piston 22 of fluid motor 2 simultaneously forces the heel 56 of the reverse shoe I5 outwardly into engagement with the brake drum. Due to the direction of rotation of the brake drum with respect to the friction members 35 and 54 on brake shoes I8 and I5, the shoes will be carried with the drum for creating a selfenergization which produces an additional braking torque, the torque of the forward shoe I8 being transmitted through the heel 40 of the shoe to the abutment M of the fluid motor 2 at the same time the torque created in reverse shoe I5 is being transmitted to the abutment 51 on fluid motor 3, which force also prevents the right hand piston I moving the toe of shoe I5 outwardly. Consequently, a portion of the torque created in the brake shoe I5 is absorbed by the right hand piston I, the majority of said torque being transmitted to the abutment 57 of fluid motor 36. Since the abutment 4! of fluid motor '2 and the abutment 51 of fluid motor 3 are radially of the center of the backing plate I, shoes I5 and I8 center themselves in such a manner that even wear of the friction members 35 and 54 will occur.

When the vehicle moves in a reverse direction, the operation of the master cylinder of the brake system will force pressure fluid, as previously described, into the fluid motors 2 and 3, forcin the right hand piston I of fluid motor 3 toward the right against the toe 55 of shoe I5, moving the shoe outwardly into engagement with the brake drum 45 while the left hand piston I of fluid motor 3 attempts to force the toe 36 of shoe I6 against the brake drum. The shoe I5 is selfenergized in a similar manner as described in the forward direction with heel 56 of the shoe remaining in contact with abutment 58 of fluid motor 2 and, as previously described, shoe I 5 will self-center itself by reason of the radial abutment 58. Although moved into engagement with the drum 45, shoe I8 is slightly de-energized because it is moved relative to the rotating "drum 45 and fails to produce a braking effect equivalent to that created by the reverse shoe I5. However, the braking effort obtained from the self-energizing reverse shoe I5 and the slightly de-energized shoe l8 isquite sufficient inasmuch as the speeds in reverse direction are far below the forward speeds. I

What I claim is: I l. A brake mechanism comprising a backing plate, a brake drum, a pair of brake shoes slidably mounted on said backing plate and adapted for engagement with said brake drum, a pair of fluid motors secured to said backing plate, one of said motors being located between the adjoin-,

ing ends of each of said shoes for movingsaid' shoes into engagement with said drum, an abutment integral with each of said motors and having a surface thereon extending radially of the center of said backing plate and brake drum and with which one end of each of said shoes engages, means adjustably mounted on one of said motors and having a surface thereon extending radially of th center of said backing plate and brake drum with which the other end of one of said shoes engages for adjusting said shoe relative to said backing plate; and means for disengaging said shoes from said brake drum.

2. A braking mechanism comprising a backing plate, a brake drum, a pair of brake shoes slidably mounted on said backing plate and adapted for engagement, with said drum, a fluid motor having a pair of pistons therein and mounted on said backing plate, a rod on one of said pistons, said motor being disposed between one of the adjoining ends of each of said shoes so that one of said pistons directly engages one end of one of said shoes, the piston rod directly engaging one end of the other of said shoes, a fluid motor disposed between the other ends of each of said shoes, a piston in said motor having a rod thereon engaging the other end of the other of said shoes, an adjustable member threaded into the second mentioned motor having a surface thereon extending radially of the center of said backing plate and drum and engageable with the other end of the other shoe which is also engageable with the piston rod of said first mentioned motor, said member adjusting the position of the last mentioned shoe relative to said backing plate; and means on said second mentioned motor having a surface thereon extending radially of the center of said drum and backing plate engageable with the other end of the shoe directly engaged by one of the pistons in said first. me tioned m t r.

3. A braking mechanism comprising a backing plate, a brake drum, a pair of brake shoes slidably mounted thereon and adapted for engagement with said brake drum, a fluid motor mounted on said backing plate and disposed between the adjoining ends of said brake shoes, a pair of pistons in said motor, one of which engages one end of one of said shoes, a rod in the other piston that engages one end of the other of said shoes,

a fluid motor mounted on said backing plate and disposed between the other adjoining ends of said shoes, a cylindrical plug member provided with a bore and threaded into said motor, a piston in said bore, a rod on said piston engageable with the other end of the shoe with which said first mentioned rod engages, means on said first mentioned fluid motor and on said plug having a surface thereon extending radially of the center of said backing plate and drum adapted to be engaged by the ends of one of said shoes; and means on the motor having the plug therein provided with a surface extending radially of the center of said backing plate with which one end of the other shoe is in engagement.

STEVE SCHNELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 635,684 Herschmann Oct. 24, 1899 1,764,178 Loughead June 17, 1930 2,030,340 White Feb. 11, 1936 2,074,434 Schnell Mar. 23, 1937 2,120,676 Oliver June 14, 1938 2,166,804 Dick July 18, 1939 2,192,293 Waseige Mar. 5, 1940 2,382,266 Stelzcr Aug. 14, 1945 

